Piston-actuating system



Dec. 6, 1960 F. soccART PIsToN-ACTUATING SYSTEM Filed June 17, 1955 NVENTO FZ Fernand SOCCAHJT ATTO R NEYS United States atent O PISTON-ACTUATNG SYSTEM Fernand Soccart, Paris, France, assigner to Societe Anonyme Franaise-pour la Separation lErnulsion et le Melange (Procds S.E.M.), Paris, France, a French corporation Filed June 17, 1955, Ser. No. 516,127

Claims priority, application France June 18, 1954 6 Claims. (Cl. 74-44) My invention relates to pumps and covers, chiey improvements in piston pumps adapted to deliver predetermined amounts of liquid with a comparatively great accuracy in the r throughput.

My invention is more particularly applicable to pumps of` this-type wherein. the throughput may be modied and adjusted with a high accuracy, preferably during the actual operation of the pump.

My invention has for its chief object the execution of'y pumps of thesaid type which areof a comparatively simpleiandcheap execution while their accuracy is very high. It is applicable both to pumps with very small throughputs and to pumps with large throughputs adapted to deliver singly several cubic meters per hour.

I obtain the results referred to in accordance with the invention by producing primarily a pumping cycle inwhich there is provided at the end of the compression stroke an idle period of a substantial duration which has for its result to allow the complete closing of the outletl` valve before the beginning of the next suction strokeythis leads to an accuracy in the throughput which is far higher than the accuracy that is obtained in prior pumps and it allows also using light valves without any springs, of a type which it was diicult to use hitherto for suchpurposes.

The operative circuit of the pump mayv furthermore and preferably incorporate also in a manner well-known per se idle periods the duration of which is substantial at the endof the suction stroke with a- View to providing for a complete filling ofV the pump body, which cooperatesalso in obtaining an excellent accuracy.

My invention provides for this result by resortingto ai piston sliding freely inside the pump body and including stops adapted to be actuated separately and alternatingly by one or more controlmembers, the alternating actuations-being separated by idle periods of substantial lengths. The shiftingof the piston` at both ends of the suction and delivery strokes is positively limited by stationarystops.

The "actuating control member or members may be constituted in particular by one or more cams which are operative during a fraction only of their rotation or else the movable stops may be controlled by a system including a connecting rod and a crank or in any other suitable manner.

Myimproved arrangement` is of a particularly interesting application in the case of measuring pumps, the throughput ofA which is to be modified and adjusted preferably during operation, independently of the adjustment of the` rhythm of the movements of the piston. This adjustment may be obtained in a simple manner by adjusting` the location of at least one of the stops rigid with the-piston` or at least one of the parts controlling saidtstops, this arrangement being associated with means for limiting` the stroke of the piston as a function of the precedingly referred to adjustment.

In these embodiments of my invention, the actuating member is adapted to act on stops rigid with the piston and impinging on saidstops while they are still moving. This produces shocks which in the case of pumps having a small throughput are practically of a reduced magnitude, but which in the case of pumps having a large throughput may` however in certain cases lead to objectionable results. According to my invention, it is possible to cut out these objectionable results by providing between the parts, which are thus brought into contact with eachother, shockabsorbing means of any suitable type.

Further objects and features of my invention will appear in the reading of the following disclosure, reference being made to the accompanying` drawings which illustrate, by way of example and` by no means in a binding sense, various embodiments of my invention. In said drawings:

Figs. 1 and 2y shows` diagrammatically two types of pumps according` to my invention, illustrated by their chief componentparts, saidpumps having an adjustable input.

Fig. 3 is amore detailedcross-section of a pump actuated in accordance ,with the diagram illustrated in Fig. 2.

Figs. 4 and 5 are simplified diagrammatic showings in plan and cross-sectional views of a star-shaped arrangement of pumps.,

In Pig. l, the piston 2 carries a pistonrod 5 `terminating witha double bent member 15, the inner section of; which 16 forms arnovable stop while its outer sec: tion 17 is provided with atappedopening inside which is threadedly engaged ascrew 18the head 19' of which formstafurthermovable stop, the two stops 16 and@ adapted. to impinge at the ends of` the piston stroke against-` the cooperating stationary stops 12 and 13j. lnsirdethe bent member `15 there moves translationally a member 20 the movements of which are` guidedby slide- Ways which are not illustrated, said` memberl being subjected to a reciprocatory, movement by a connecting rod orpitman andcrank system 21, 2.2, 23, 24. As already mentioned,`12 and 13 designatestationary stops against which the movable stops 19 and 16 on the, member 15 beati respectively at` the end of the suction stroke and ofthe delivery stroke. lt` is apparent that the stroke of the piston is equal, ontheone hand,` to `the distance separating thestops 12 and 13 minus the distance separating the movable stops 16 and 19 and on the other handto twice the length of the.A crank 2d minus the clearance provided for. the member 21B between the` cooperating stops, respectively 26` on theinside ofthebentmember 15 and the end 27` of the adjustable screw, which stops. face the opposite` ends of, said-member 20. Now., by` screwing more `or less the screw 1S into the` outer section-j 17 of the member 15, this reduces by a` corresponding amount the` clearance for the member-..20` between the, stops 26 and 27.

lt is apparent that, it the` screw- 18A is suiciently unscrewed for the dis-tance between` the,` stops 16` and 19 to become equal tothe distance between the stops 12 and 13, the piston rod is held fast and the pistonA remains stationary. On the other hand, the clearance leftopen between the inner stops 26 and 27 for the shifting of the member 20 is equal to twice the length ofthe-crank so that the crank may revolve freely while the member 20, reciprocates freely between the stops 26 and 2,7;` as the4 screw is being` screwed` into the section 1,7, the distance `between, the stops 16 and- 19` decreases whereby the stroke of the piston increases. At the same time the clearance provided for the member 2,6) between the inner stops 26 and 27 decreasesf and the member 20 the stroke of which is obviously constant willurge alternatingly towards the right hand side and towards the left hand side` the stops 26 andj 27' whereby the piston rod will assume a reciprocating movement.

Now, if the screw 18 is screwed still further into the member 17, a moment comes at which the clearance provided in the member 20 between the stops 26 and 27 gives the piston its maximum stroke. It should be remarked that in this case the pump operates in the manner of a conventional pump without any idle periods at the ends of its strokes. It is obviously preferable in practice not to use the pump described under such conditions, corresponding to a zero clearance, since this cuts out immediately the advantages provided by the idle periods.

Fig. 2 illustrates a modiiied embodiment and more precisely a modiiication of Fig. 1 wherein the actuation of the pump is performed no longer through a connecting rod and crank system but through an eccentric cam 28, which takes the place of the member 20 and engages the space between the stops 26 and 27, the latter stop being constituted by the tip of the screw 18. In this case, the cam revolving round its axis 29 acts in succession on the two stops so as to give the piston a reciprocatoryv movement which is the same as in the preceding case. Supposing the cam is an eccentric circular cam, the stroke of the piston is equal to twice the eccentricity of the cam i.e. the distance between the centre of the cam and its rotary axis 29 minus the clearance of said cam in the space separating the stops 26 and 27, said clearance being in its turn equal to the distance betwene the stops 26 and 27 minus the diameter of the cam.A

Fig. 3 illustrates in a more detailed manner an embodiment of a cam arrangement of the type the principle of which has been disclosed with reference to Fig. 2. In said Fig. 3, 31 designates the frame adapted to contain the mechanical control system for the piston while 32 designates the pump body carried at the end of said frame 1. Inside said pump body, is movably mounted a plunger piston 33 fluidtightness for which is obtained by means of a packing 34. The piston carries a rod 35 sliding inside a bearing 36 carrying a stop 16 for the strap 37 rigid with said rod 35 and ending with a sleeve 38, slidingly engaging a bearing 39; it will be noticed that the sliding means 35 are arranged coaxially with the sliding means 38. To the front end of the strap, i.e. the end nearest the plunger piston, is secured a stop 40 adapted to cooperate with a cam 41 constituted in the particular embodiment illustrated by an eccentric ball bearing revolubly mounted with reference to the spindle 42. The actual movement of the cam is controlled by a power unit which is not illustrated, or through a suitable driving and speed reducing arrangement. The plane in which the strap 37 lies is shifted with reference to the plane of the cam 42 either towards the front of the figure or towards the rear thereof so as not to hinder the rotary movement of said cam 41 round its axis 42. 1nside the sliding sleeve 38 which is tapped for this purpose, is arranged a threaded rod 43 adapted to be screwed inside said sleeve 38; the threaded rod 43 carries at its left hand end a stop 44 adapted to cooperate with'the cam 41 while its right hand end forms a smooth surfaced cylinder adapted to slide inside a socket 46, which socket is revolubly carried inside a bearing 47 located beyond the bearing 39 and coaxial therewith. Said bearing 47 is however longitudinally stationary with reference to said bearing 39.

Inside the socket 46 is provided a longitudinal groove 48 engaged by a stud 49 rigid with the smooth-surfaced cylinder 45. Consequently when the socket 46 is caused to rotate, it drives through said interengaging stud 39 and groove 48 the cylinder 45 into rotation, whereby the threaded rod 43 is constrained to screw into or out of the sleeve 38 and this leads to a shifting of the unit constituted by the parts 43--44 and 45 towards the right hand side or towards the left hand side; the rotary movement of the socket 46 is obtained for instance by means of a control handle 50 rigid with said socket 46. Furthermore, a gearing 51 connects the socket 46 with a drum 52 whereby it is possible to deiine at any moment the end of the suction stroke, said unit abuts against the bottom 98 of the socket 46, the position of the stop formed by said bottom being adjustable at the moment of the mounting as provided for instance by a screw 91 screwed inside the rear of the cylinder 45. The latter being thus held against its stop, the strap remains stationary, the cam 41 is assumed to be in contact with the stop 44 through its part of maximum eccentricity and will engage again the stop 40 after a more or less considerable number of revolutions as dened by the adjustment of the distance separating the stops 40 and 44 which adjustment has been provided through the handle 50.

For the adjusted position corresponding to the maximum spacing between the stops 40 and 44, the cam will rotate without actuating the piston in either direction. This forms the adjustment corresponding to a zero throughput. On the other hand, for the minimum spacing between the stops 40 and 44, the cam will urge the stop 40 back as soon as it has moved away from engagement with the abutment 44. This adjustment provides a maximum stroke for the piston and consequently a maximum throughput.

The intermediate adjusted positions will produce all the intermediate throughputs between zero and a maximum.

To the front of the cylinder 32 is located the valve case provided with the input and output ports for the liquid, which ports communicate with the suction and delivery pipes located side by side as well-known in the art and of which only the delivery pipe is shown at 92 (Fig. 3).

It is possible also to describe my invention as follows, reference being made to Figs. 1 and 2 in which I may consider the arrangement as including four stops respectively at 16, 19, 13 and 12, while two thrust members 26 and 27 are carried by the piston rod to face the opposite ends of the reciprocating control member 20, the second thrust member being adjustably secured to said rod and being constituted by the tip of screw 18, which also forms advantageously the second stop 19. The control member constituted by the member 20 which assumes a reciprocating movement urges thus alternatingly the rst and the second thrust members outwardly at the end of its stroke to make the corresponding rst and second stops 16 and 19 engage correspondingly the cooperating third and fourth stops 13 and 12. Thus, the displacement of the control member 20 is equal to the distance separating the second stop 49 from the fourth stop 12 when the control member engaging the rst thrust member 26 has set the irst stop 16 in contact with the third stop 13 and the second thrust member 27 has been set in an extreme position for which it engages the control member on the side thereof facing away from its point of contact with the first thrust member 26.

There is also provided in accordance with my invention an arrangement inside the output pipe for checking whether the valve is in a suitable operative state. This arrangement includes chiefly a ball 61 adapted to move between two extremestops 62 and 63. When the delivery valve operates accurately the ball is`constantly held in the position illustrated i.e. in a position on the downstream end with reference to the flow of liquid.

In the case of a defective operation of the valve, the corresponding ball. runs rearwardly and impinges against the stop 63. This movement of the ball is made apparent either by providing round it a pipe section of transparent material so as to allow direct inspection of the location of the ball or else by surrounding the delivery pipe by a magnetic or electromagnetic device 64 connected with any suitable indicating or recording means adapted to operate when the ball is shifted between its stops.

The actual measuring pump operates as follows: When the spacing between the stops 44 and 40 has been brought through action on the handle 50 to its maximum value, the rotary cam engages periodically through a sliding contact therewith said stops 40 and 44 without acting on them so that the throughput is consequently reduced to zero.

Now, if the handle 50 is operated so as to bring the unit 43-44, 45 into an intermediate position on its path such as that illustrated in the drawing for which the spacing between the stops 4t) and 44 is less than in the preceding case, the cam 41 acts as it rotates during the compression stroke on the stop 40 so as to urge it back into the position illustrated. This being done, the cam continues rotating and engages after a predetermined fraction of its stroke the stop 44 so as to urge it in the opposite direction until it has returned into a position opposed to that illustrated in the drawing and for which the screw 91 on the unit 43, 44, 45, is in contact with the bottom 90 of the socket 46.

Thecam continuing its rotary movement will then release the stop 44 and engages again the stop 40 which urges then towards the left hand side the piston 35 to return same into the position illustrated.

The arrangement illustrated in Figs. 4 and 5 shows an arrangement of a plurality of measuring pumps, three in the case illustrated, which are actuated by a common cam. Fig. 4 is a plan view of this arrangement and Fig. 5 an axial cross section on a larger scale.

In Fig. 4, the.three pumps 66, 67, 68, are located at the three apices of an equilateral triangle, the axes of their pistons converging all at the centre of said triangle, Each pump system includes as illustrated in Fig. 5, a strap 69 of a type similar to that disclos^d hereinabove but a single cam 41 acts on the stops 40 and 44 provided on each of said straps so as to serve all the three pumps.

The straps of the three pumps are shifted vertically with reference to each other so that their movements may not interfere with one another, this shifted arrangement not being illustrated; it will be readily ascertained that under such conditions the cam the rotation of which is controlled for instance by a motor 70 acts in succession on the three pumps, the movement of each pump with reference to the preceding pump being shifted by 120. This arrangement allows on the one hand, obtaining through a single cam the control of the movement of three pumps, which is an advantage for large throughputs and on the other hand it provides for this phase shifting through 120 which, if the inputs of the different pumps and their outputs respectively are interconnected, ensures an extremely uniform ow of liquid while the total power absorbed is reduced to a minimum. The arrangement which has been described with reference to Figs. 4 and 5 allows actuating three pumps through the same cam. Now it may be of interest when it is desired to obtain large throughputs to resort to a larger number of pumps controlled by the same cam. It is then of advantage to actuate simultaneously pairs of pumps in tandem relationship in which case a hexagonal arrangement such as that described allows actuating simultaneously no longer three pumps but six pumps.

What I claim is:

1. In a system for actuating a piston, the combination of a piston rod rigid with the piston and adapted to assume therewith a reciprocatory axial movement, a first stop rigid with said rod, a second stop secured to said rod at an adjustable axial distance from the first stop, a third stationary stop cooperating with said rst stop on the side thereof facing away from the second stop, a fourth stationary stop cooperating with the second stop on the side thereof facing away from the first stop, a thrust member intergral with said piston rod, a second thrust member adjustably secured to said rod with a free space between said thrust members, means for axially adjusting the position of said thrust member on the rod between two extreme positions and simultaneously maintaining said thrust member at a predetermined invariable axial distance from said second stop, a control member engaging the space between the two thrust members and adapted to assume a reciprocating movement and to urge alternatingly the first and the second thrust members at the ends of its stroke in an axial direction facing away from the other thrust member to make the corresponding first and second stops engage correspondingly the cooperating stationary third .and fourth stops, the displacement of the control member being equal to the distance separating the second stop from the cooperat. ing fourth stop when the control member engaging the rst thrust member has set the first stop in contact with the third stop after adjustment of the second thrust member in an extreme position for which it engages the control member on the side thereof facing away from its point of contact with the first thrust member.

2. A piston-actuating system comprising a piston, a piston rod, a first stop rigid with the piston rod, a second stop adjustably secured to said piston rod at an adjustable distance from the first stop, a third and a fourth stationary stop located on the outside of the first and second stops with reference to the second and first stops respectively and defining the stroke of the piston rod, a first and a second thrust member rigid with the first and the second stop respectively, means controlling the location of the second stop axially of the piston rod and of the thrust member rigid therewith, an actuating system including a member adapted to execute a reciprocation equal to the maximum stroke to be provided for the piston between the two thrust members and to urge during the corresponding ends of its reciprocation each thrust nvmber in a direction facing away from the other thrust member to urge the corresponding stop of the first two stops against the corresponding stationary stop.

3. In a system for actuating a piston, the combination of a piston rod rigid with the piston and adapted to assume therewith a reciprocatory axial movement, a rst stop rigid with said rod, a second stop secured to said rod at an adjustable axial distance from the first stop, a third, stationary stop cooperating with said first stop on the side thereof facing away from the second stop, a fourth, stationary stop cooperating with the second stop on the side thereof facing away from the first stop, a thrust member integral with said piston rod, a second thrust member adjustably secured to said rod with a free space between said thrust members, means for axially adjusting the position of said thrust member on the rod between two extreme positions and simultaneously maintaining said thrust member at a predetermined invariable axial distance from said second stop, an eccentric cam adapted to rotate in the space between the two thrust members to urge alternatingly the first and the second thrust members at the ends of its stroke in an axial direction facing away from the other thrust member to make the corresponding first and second stops engage correspondingly the cooperating Stationary third and fourth stops, the displacement of the extreme points of the cam along an axial line passing through its center being equal to the distance separating the second stop from the cooperating fourth stop when the control member engaging the first thrust member has set the first stop in contact with the third stop after adjustment of the second thrust member in an extreme position for which it engages the control member on the side thereof facing away from its point of contact with the first thrust member.

4. In a system for actuating a piston, the-combination of a piston rod rigid with the piston and adapted to assume therewith a reciprocatory axial movement, a first stop rigid with said rod, a second stop secured to said rod at an adjustable axial distance from the rst stop, a third, stationary stop cooperating with said first stop on the side thereof facing away from the second stop, a fourth, stationary stop cooperating with the second stop on the side thereof facing away from the first stop, a thrust member integral with said piston rod, a second thrust member adjustably secured to said rod with a free space between said thrust members, means for axially adjusting the position of said thrust member on the rod between two extreme positions and simultaneously maintaining said thrust member at a predetermined invariable axial -distance from said second stop, a control member slidably reciprocatable in the space between the two thrust members, a crank and a pitman system controlling the reciprocation of said sliding member throughout a stroke of constant length to make said control member urge alternatingly the first and the second thrust members at the ends of its stroke in an axial direction facing away from the other thrust member to make the corresponding first and second stops engage correspondingly the cooperating stationary third and fourth stops, the displacement of the control member being equal to the distance separating the second stop from the cooperating fourth stop when the control member engaging the first thrust member has set the first stop in contact with the third stop after adjustment of the second thrust member in an extreme position for which it engages the control member on the side thereof facing away from its point of contact with the rst thrust member.

5. In a system for actuating a piston, the combination of a piston rod rigid with the piston and adapted to assume therewith a reciprocatory axial movement, an extension of the piston rod including a laterally offset section, a first stop rigid with the piston rod, a screw coaxial with the axis of the piston rod and threadedly engaging the outer end of said extension and the first end of which facing away from the first stop forms a second stop, a third, stationary stop cooperating with said first stop on the side thereof facing away from the second stop, a fourth, stationary stop cooperating with the second stop on the side thereof facing away from the first stop, a thrust member integral with the piston rod and facing the second end of the screw, said second end forming a second thrust member, a control member engaging the space between the two thrust members and adapted to assume a reciprocating movement and to urge alternatingly the first and the second thrust members at the ends of its stroke in an axial direction facing away from the other thrust member to make the,

corresponding first and second stops engage correspondingly the cooperating stationary third and fourth stops, the displacement of the control member being equal to the vdistance separating the second stop from the cooperating fourth stop when the control member engaging the first thrust member has set the rst stop in contact with the third stop after adjustment of the second thrust member in an extreme position for which it engages the control member on the side thereof facing away from its point of contact with the first thrust member.

6. In a. system for actuating a piston, the combination of av piston rod rigid with Vthe piston and adapted to assume therewith a reciprocatory axial movement, a first stop rigid with said rod, a second stop'secured to said rod at an adjustable axial distance ,from the first stop, a third, stationary stop cooperating with said rst stop, on the side thereof facing away from the second stop, a fourth, stationary stop cooperating with the second stop on the side thereof facing away from the first stop, a thrust member integral with said piston rod, a second thrust member adjustably secured to said rod with a free space between said thrust members, means on the outside of the fourth, stationary stop for the manual, simultaneous adjustment of the first stop and second thrust member with an unvarying spacing between the latter, a control member engaging the space between the two thrust members and adapted to assume a reciprocating movement and to urge alternatingly the first and the second thrust members at the ends of its stroke in an axial direction facing away from the other thrust member to make the corresponding first and second stop engage the cooperating stationary third and fourth stops, the displacement of the control member being equal to the maximum stroke to be provided for the piston.

References Cited in the le of this patent UNITED STATES PATENTS 648,628 McCanna May 1, 1900 836,234 Zeyen Nov. 20, 1906 838,565 McCanna Dec. 18, 1906 1,008,401 Woerner Nov. 14, 1911 1,062,377 Woerner May 30, 1913 1,099,229 Woerner June 9, 1914 1,494,764 Wishart May 20, 1924 1,595,917 Owen Aug. l0, 1926 1,909,955 'Herbsrnan et al. May 23, 1933 2,450,248 Morgan et a1. Sept. 28, 1948 FOREIGN PATENTS 114,741 Austria Oct. 25, 1929 491,060 Italy Feb. 23, 1954 

